Process and apparatus for hydrogen and carbon production via carbon aerosol-catalyzed dissociation of hydrocarbons

ABSTRACT

The present invention relates to a novel process for sustainable, continuous production of hydrogen and carbon by catalytic dissociation or decomposition of hydrocarbons at elevated temperatures using in-situ generated carbon particles. Carbon particles are produced by decomposition of carbonaceous materials in response to an energy input. The energy input can be provided by at least one of a non-oxidative and oxidative means. The non-oxidative means of the energy input includes a high temperature source, or different types of plasma, such as, thermal, non-thermal, microwave, corona discharge, glow discharge, dielectric barrier discharge, or radiation sources, such as, electron beam, gamma, ultraviolet (UV). The oxidative means of the energy input includes oxygen, air, ozone, nitrous oxide (NO 2 ) and other oxidizing agents. The method, apparatus and process of the present invention is applicable to any gaseous or liquid hydrocarbon fuel and it produces no or significantly less CO 2  emissions compared to conventional processes.

The present invention is related to hydrogen production methods, and, inparticular, to a process and an apparatus for the production of hydrogenand carbon via catalytic dissociation of methane and other hydrocarbons.

BACKGROUND AND PRIOR ART

Hydrogen is universally considered a fuel of the future due toenvironmental advantages over conventional (i.e., fossil-based) fuels.Another important advantage of using hydrogen stems from the fact thatit could be electrochemically (i.e., without Carnot-cycle limitation)converted into electricity with very high energy conversion efficiencyusing fuel cells (FC).

To be used in energy conversion devices, hydrogen has to be produced andstored; however, each of these aspects of hydrogen technology isassociated with major technological challenges.

With regard to production, hydrogen can be produced from hydrocarbonfuels, such as, methane (CH₄), and natural gas (NG), via oxidativereforming or thermal (thermocatalytic) decomposition processes.

Oxidative reforming involves the reaction of hydrocarbons with oxidants:water, oxygen, or a combination thereof; the corresponding processes aresteam reforming, partial oxidation and autothermal reforming,respectively. As a first step, these processes produce a mixture ofhydrogen with carbon monoxide (synthesis-gas), which is followed bywater gas shift and CO₂ removal stages. The total CO₂ emissions fromthese processes exceed 0.4 m³ per each m³ of hydrogen produced.

Thermal (thermocatalytic) decomposition or dissociation of hydrocarbonsoccurs at elevated temperatures (500-1500° C.) in an inert (oroxidant-free) environment and results in the production of hydrogen andelemental carbon. Due to the lack of oxidants, no carbon oxides areproduced in the process. This eliminates or greatly reduces carbondioxide (CO₂) emissions and obviates the need for water gas shift andCO₂ removal stages, which significantly simplifies the process. Theprocess produces pure carbon as a valuable byproduct that can bemarketed, thus reducing the net cost of hydrogen production. Thefollowing is a brief description of the prior art with regard tohydrocarbon thermal (thermocatalytic) decomposition technologies.

Thermal decomposition of natural gas (NG), known as the Thermal Blackprocess, has been practiced for decades as a means of production ofcarbon black (Kirk-Othmer Encyclopedia of Chemical Technology, vol. 4,pages 651-652, Wiley & Sons, 1992). In this process a hydrocarbon streamwas pyrolyzed at high temperature (1400° C.) over the preheated contact(firebrick) into carbon black particles and hydrogen, which was utilizedas a fuel for the process. The process was employed in a semi-continuous(i.e., cyclic pyrolysis-regeneration) mode using two tandem reactors.

U.S. Pat. No. 2,926,073 to Robinson et al. describes the improvedcontinuous process for making carbon black and byproduct hydrogen bythermal decomposition of natural gas (NG). In this process, NG isthermally decomposed to carbon black and hydrogen gas is used as aprocess fuel in a bank of heated tubes at 982° C.

Thus, both technological approaches described above, target theproduction of only one product: carbon black, with hydrogen being asupplementary fuel for the process.

Kvaerner Company of Norway has developed a methane decompositionprocess, which produces hydrogen and carbon black by using hightemperature plasma (CB&H process described in the Proceedings of 12^(th)World Hydrogen Energy Conference, Buenos Aires, p. 637-645, 1998). Theadvantages of the plasmochemical process are high thermal efficiency(>90%) and simplicity, however, it is an energy intensive process.

Steinberg et al. proposed a methane decomposition reactor consisting ofa molten metal bath in Int. J. Hydrogen Energy. 24, 771-777, 1999.Methane bubbles through molten tin or copper bath at high temperatures(900° C. and higher). The advantages of this system are: an efficientheat transfer to a methane gas stream and ease of carbon separation fromthe liquid metal surface by density difference.

Much research on methane decomposition over metal and carbon-basedcatalysts has been reported in the literature. Transition metals (e.g.Ni, Fe, Co, Pd, and the like.) were found to be very active in methanedecomposition reaction; however, there was a catalyst deactivationproblem due to carbon build up on the catalyst surface. In most cases,surface carbon deposits were combusted by air (or gasified by steam) toregenerate the catalyst's original activity resulting in large amountsof CO₂ byproduct.

For example, Callahan describes “a fuel conditioner” designed tocatalytically convert methane and other hydrocarbons to hydrogen forfuel cell applications in Proc. 26th Power Sources Symp. Red Bank, N.J,181-184, 1974. A stream of gaseous fuel entered one of two reactor beds,where hydrocarbon decomposition to hydrogen took place at 870-980° C.and carbon was deposited on the Ni-catalyst. Simultaneously, air enteredthe second reactor where the catalyst regeneration occurred by burningcoke off the catalyst surface. The streams of fuel and air were reversedfor another cycle of decomposition-regeneration. The reported processdid not require water gas shift and gas separation stages, which was asignificant advantage. However, due to cyclic nature of the process,hydrogen was contaminated with carbon oxides. Furthermore, no carbonbyproduct was produced in this process.

U.S. Pat. No. 3,284,161 to Pohlenz et al. describes a process forcontinuous production of hydrogen by catalytic decomposition of NG.Methane decomposition was carried out in a fluidized bed catalyticreactor in the range of temperatures from 815° C. to 1093° C. SupportedNi, Fe and Co catalysts (preferably, Ni/Al₂O₃) were used in the process.The deactivated (coked) catalyst was continuously removed from thereactor to the regenerator where carbon was burned off, and theregenerated catalyst was recycled to the reactor.

U.S. Pat. No. 2,476,729 to Helmers et al. describes the improved methodfor catalytic cracking of hydrocarbon oils. It was suggested that air isadded to the feedstock to partially combust the feed such that the heatsupplied is uniformly distributed throughout the catalyst bed. This,however, would contaminate and dilute hydrogen with carbon oxides andnitrogen.

Use of carbon catalysts offers the following advantages over metalcatalysts: (i) no need for the regeneration of catalysts by burningcarbon off the catalyst surface, (ii) no contamination of hydrogen bycarbon oxides, and (iii) carbon is produced as a valuable byproduct ofthe process. Muradov has reported on the feasibility of using differentcarbon catalysts for methane decomposition reaction in Energy & Fuel,12, 41-48, 1998; Catalysis Communications. 2, 89-94, 2001.

U.S. Pat. No. 2,805,177 to Krebs describes a process for producinghydrogen and product coke via contacting a heavy hydrocarbon oil admixedwith a gaseous hydrocarbon with fluidized coke particles in a reactionzone at 927° C.-1371° C. Gaseous products containing at least 70 volume% of hydrogen were separated from the coke, and a portion of cokeparticles was burnt to supply heat for the process; the remainingportion of coke was withdrawn as a product.

U.S. Pat. No. 4,056,602 to Matovich teaches high temperature thermaldecomposition of hydrocarbons in the presence of carbon particles byutilizing fluid wall reactors. Thermal decomposition of methane wasconducted at 1260° C.-1871° C. utilizing carbon black particles asadsorbents of high flux radiation energy, and initiators of thepyrolytic dissociation of methane. It was reported that 100% conversionof methane could be achieved at 1815° C. at a wide range of flow rates(28.3-141.5 l/min).

U.S. Pat. No. 5,650,132 to Murata et al. describes the production ofhydrogen from methane and other hydrocarbons by contacting them withfine particles of carbonaceous materials. The carbonaceous materialsincluded carbon nanotubes, activated charcoal, fullerenes C₆₀-C₇₀,finely divided diamond powder as well as soot obtained by thermaldecomposition (or combustion) of different organic compounds or by arcdischarge between carbon electrodes in vacuum. The optimal conditionsfor methane conversion included: preferable methane concentration: 0.8-5volume % (balance inert gas), the temperature range of 400° C.-11,200°C. and residence times 0.1-50 sec.

U.S. Pat. No. 6,670,058 to Muradov describes the continuous process forhydrogen and carbon production using carbon-based catalysts. The processemploys two fluid-solid vessels: a reactor and a heater/regenerator withcarbon particles circulating between the vessels in a fluidized state.NG enters a fluidized bed reactor (FBR) where it is decomposed over afluidized bed of catalytically active carbon particulates at thetemperature range of 850° C.-900° C. The resulting hydrogen-rich gasenters a gas separation unit where a stream of hydrogen with a purityof >99.99 volume % is separated from the unconverted methane, which isrecycled to the FBR. The carbon particles are directed to a fluidizedbed heater where they are heated to 1000-1100° C. by hot combustiongases containing steam and CO₂, and simultaneously activated. The mainportion of carbon particles is withdrawn from the system as a product.

In summary, the major problem with respect to metal- andcarbon-catalyzed decomposition of hydrocarbons relates to gradualdeactivation of the catalysts during the process. The deactivation couldmainly be attributed to the inhibition of the catalytic process by thecarbon deposits blocking the catalyst active sites. This necessitatesthe regeneration of the catalysts either by complete combustion orgasification of the carbon deposits, in case of metal catalysts orpartial gasification of carbon deposits, in case of carbon-basedcatalysts.

The regeneration step significantly complicates the process and resultsin contamination of hydrogen with carbon oxides, necessitating anelaborate hydrogen purification step and production of considerableamount of CO₂ emission. Thus, there is a need for a more efficient,simple, versatile and sustainable process for the production of hydrogenand carbon from different hydrocarbons without catalyst regeneration andwith drastically reduced CO₂ emission when compared to conventionalprocesses.

The present invention improves upon and overcomes many of thedeficiencies of the prior art.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to develop a sustainablecontinuous process for hydrogen and carbon production by catalyticdissociation or decomposition of hydrocarbons with drastically reducedCO₂ emission.

A second objective of the present invention is to provide a process forthe continuous production of hydrogen and carbon via decomposition ofhydrocarbon feedstock over carbon aerosol particles acting as a catalystfor the process.

A third objective of the present invention is to provide a process forcontinuous production of hydrogen and carbon via catalytic decompositionof hydrocarbons over carbon aerosol particles produced from carbonaceousmaterials including, but not limited to, hydrocarbons, carbon monoxide,alcohols, esters, carbohydrates, biomass, and the like.

A fourth objective of the present invention is to provide a process forcontinuous production of hydrogen and carbon via catalytic decompositionof hydrocarbons over carbon aerosol particles produced from carbonaceousmaterials in response to an energy input such as a high temperaturesource, plasma, irradiation, and the like.

A fifth objective of the present invention is to provide a process forhydrogen production from any gaseous or liquid hydrocarbon including,but not limited to, methane, natural gas, liquefied petroleum gas,gasoline, diesel fuel, sulfurous hydrocarbon fuels.

A sixth objective of the present invention is to provide an apparatusfor the continuous production of hydrogen and carbon via decompositionof hydrocarbon feedstock over in-situ generated carbon aerosol particlesacting as a catalyst for the process.

A seventh objective of the present invention is to provide an apparatusthat combines, in one continuous process, the oxidative andnon-oxidative means of generation of carbon aerosol particles fromcarbonaceous materials to catalyze a single-step, in-situ decompositionof hydrocarbon feedstock to produce hydrogen gas and elemental carbon.

A preferred method for producing hydrogen and elemental carbon fromhydrocarbon feedstock using a continuous process includes selecting areactor vessel having a first reaction compartment for generating carbonparticles connected to a second reaction compartment that is a catalyticreactor for dissociation of hydrocarbon feedstock into hydrogen gas andcarbon, selecting a carbonaceous material that can be converted tocarbon particles, transporting the carbonaceous material to the firstreaction compartment where the carbonaceous material is exposed to anenergy input that produces an outgoing stream of carbon particles, then,directing the outgoing stream of carbon particles to the second reactioncompartment, then, sending a stream of hydrocarbon feedstock to thesecond reaction compartment where dissociation of the hydrocarbonfeedstock occurs over the surface of carbon particles, and collectinghydrogen gas from a first outlet and carbon product from a second outletof the second reaction compartment.

The preferred carbonaceous material is a substance rich in carbon and isreadily converted to carbon particles when exposed to an energy inputthat achieves temperatures in a range from approximately 100° C. toapproximately 5000° C., temperatures sufficient to convert carbonaceousmaterials to carbon particles in the first reaction compartment.

The preferred energy input is provided by at least one of anon-oxidative means, an oxidative means, and mixtures thereof. Thepreferred non-oxidative means of energy input includes, but is notlimited to, at least one of a high temperature source, plasma, andirradiation. The preferred oxidative means of energy input is an oxidantselected from at least one of air, oxygen, ozone and nitrous oxide.

The preferred carbonaceous material is a substance with a formula ofC_(p)H_(q)X_(r), where X is an element including, at least one ofoxygen, nitrogen, sulfur, phosphorus, and p≧1, q≧0, r≧0 The morepreferred carbonaceous material includes hydrocarbons and oxygen-,nitrogen-, sulfur- and phosphorus-containing organic compounds,including, at least one of methane, ethylene, propylene, acetylene,benzene, toluene, acetic acid, propanol, carbon disulfide and mixturesthereof, carbon monoxide (CO), carbohydrates and biomass.

The preferred hydrocarbon feedstock is a hydrocarbon with the formulaC_(n)H_(m) wherein n≧1, and (2n+2)≧m≧n. The more preferred hydrocarbonfeedstock includes methane, natural gas, propane, liquefied petroleumgas (LPG), naphtha, gasoline, kerosene, jet-fuel and diesel fuel.

Another preferred method for producing hydrogen and carbon fromhydrocarbon feedstock using a continuous process includes selecting areactor vessel having a first reaction compartment for generating carbonparticles connected to a second reaction compartment that is a catalyticreactor for dissociation of hydrocarbon feedstock into hydrogen gas andcarbon, selecting a hydrocarbon feedstock that is capable of conversionto carbon particles and capable of dissociation into hydrogen gas andcarbon, dividing the hydrocarbon feedstock into a first stream and asecond stream, transporting the first stream of hydrocarbon feedstock tothe first reaction compartment where the hydrocarbon is exposed to anenergy input that produces an outgoing stream of carbon particles,directing the outgoing stream of carbon particles to the second reactioncompartment, sending the second stream of hydrocarbon feedstock to thesecond reaction compartment where dissociation of the hydrocarbonfeedstock occurs over the surface of carbon particles flowing from thefirst reaction compartment, and collecting hydrogen gas from a firstoutlet and carbon product from a second outlet of the second reactioncompartment.

The preferred hydrocarbon feedstock is a compound with the formulaC_(n)H_(m) wherein n≧1, and (2n+2)≧m≧n and is preferably hydrocarbonfeedstock of saturated hydrocarbons, unsaturated hydrocarbons, andaromatic hydrocarbons.

The preferred hydrocarbon feedstock is readily converted to carbonparticles when exposed to an energy input that achieves temperatures ina range from approximately 100° C. to approximately 5000° C. in thefirst reaction compartment. The preferred energy input is provided by atleast one of a non-oxidative means, an oxidative means and a mixturethereof. The non-oxidative means of the energy input includes at leastone of a high temperature source, plasma, and irradiation; whereas, theoxidative means of energy input includes an oxidant selected from atleast one of air, oxygen, ozone and nitrous oxide.

A preferred apparatus for producing hydrogen and carbon from hydrocarbonfeedstock using a continuous process includes a reactor vessel having afirst reaction compartment for generating carbon particles connected toa second reaction compartment that is a catalytic reactor fordissociation of hydrocarbon feedstock into hydrogen gas and carbon, ameans for transporting a carbonaceous material that is converted tocarbon particles to the first reaction compartment where thecarbonaceous material is exposed to an energy input that produces anoutgoing stream of carbon particles, a means for directing the outgoingstream of carbon particles to the second reaction compartment, a meansfor transporting a stream of hydrocarbon feedstock to the secondreaction compartment where dissociation of the hydrocarbon feedstockoccurs over the surface of carbon particles from the first reactioncompartment, and a means for collecting hydrogen gas from a first outletand carbon product from a second outlet of the second reactioncompartment.

The preferred energy input to the first reaction compartment achievestemperatures in a range from approximately 100° C. to approximately5000° C. and is provided by at least one of a non-oxidative means, anoxidative means, and a mixture thereof. The preferred non-oxidativemeans of the energy input is at least one of a high temperature source,plasma, and irradiation. The preferred oxidative means of the energyinput is an oxidant selected from at least one of air, oxygen, ozone andnitrous oxide.

Another preferred apparatus for producing hydrogen and carbon fromhydrocarbon feedstock using a continuous process includes a reactorvessel having a first reaction compartment for generating carbonparticles connected to a second reaction compartment that is a catalyticreactor for dissociation of hydrocarbon feedstock into hydrogen gas andcarbon, a means for dividing a hydrocarbon feedstock into a first streamthat is converted to carbon particles and a second stream that isdissociated into hydrogen gas and elemental carbon, a means fortransporting the first stream of hydrocarbon feedstock to the firstreaction compartment where the hydrocarbon is exposed to an energy inputthat produces an outgoing stream of carbon particles, a means fordirecting the outgoing stream of carbon particles to the second reactioncompartment, a means for transporting the second stream of hydrocarbonfeedstock to the second reaction compartment where dissociation of thehydrocarbon feedstock occurs over the surface of carbon particles fromthe first reaction compartment, and a means for collecting hydrogen gasfrom a first outlet and carbon product from a second outlet of thesecond reaction compartment.

The preferred energy input achieves temperatures inside the firstreaction compartment in a range from approximately 100° C. toapproximately 5000° C. and is provided by at least one of anon-oxidative means, an oxidative means, and a mixture thereof. Thepreferred non-oxidative means of the energy input is at least one of ahigh temperature source, plasma, and irradiation and the preferredoxidative means of the energy input is an oxidant selected from at leastone of air, oxygen, ozone, and nitrous oxide.

Further objects and advantages of the present invention will be apparentfrom the following detailed description of a presently preferredembodiment which is illustrated schematically in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows simplified schematics of the general concept of the presentinvention.

FIG. 2 shows schematics of the present invention where carbonaceousmaterial is a hydrocarbon.

FIG. 3 is a schematic diagram of the process and apparatus for theproduction of hydrogen and carbon from a hydrocarbon feedstock.

FIG. 4 is a perspective view of the reactor FIG. 5 is a plan view of thereactor

FIG. 6 shows schematics of the experimental unit for production ofcarbon aerosol particles

FIG. 7 is a graph of the kinetics of methane decomposition over carbonaerosol particles produced by non-thermal plasma using differentelectrode materials

FIG. 8 provides experimental data on methane catalytic decompositionusing carbon aerosol particles produced by non-thermal plasma.

FIG. 9 is a scanning electron micrograph (SEM) image of carbon producedby non-thermal plasma-assisted decomposition of methane.

FIG. 10 is a transmission electron micrograph (TEM) image of carbonproduced by non-thermal plasma-assisted decomposition of methane

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before explaining the disclosed embodiments of the present invention indetail it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangements shown sincethe invention is capable of other embodiments. Also, the terminologyused herein is for the purpose of description and not of limitation.

The terms, “carbon” and “elemental carbon” are used interchangeablyherein when referring to the product of the dissociation ofhydrocarbons.

The terms, “carbon particles” (CP), “carbon aerosol particles” (CAP),and “carbon aerosols” are used interchangeably herein when referring tothe carbon particles produced in the CAP generator that subsequentlyfunction as catalysts in the catalytic converter portion of theapparatus of the present invention.

“Carbonaceous material” as used herein means any substance rich incarbon, which is capable of yielding carbon particles (CP) or carbonaerosol particles (CAP) with the application of energy. The energy inputused to convert the carbonaceous material (CM) to carbon particles thateasily can become airborne, can be applied via non-oxidative andoxidative means.

The non-oxidative means of the energy input implies that no oxidizingagents are used during production of carbon particles; this include theuse of plasma, irradiation and various high temperature sources such asa hot filament, a heating element, a catalytic burner, and the like,wherein the temperatures obtained during the energy input is in a rangefrom approximately 100° C. to approximately 5000° C. The irradiationenergy input occurs at lower temperatures, such as approximately 100° C.and thermal plasma temperatures can be as high as approximately 5000° C.or even higher.

The oxidative means of the energy input implies that the production ofcarbon particles occurs during high-temperature transformation ofcarbonaceous (CM) in the presence of oxidizing agents such as oxygen,air, ozone, hydrogen peroxide, NO₂, and the like, wherein thetemperatures obtained during the energy input is in a range fromapproximately 400° C. to approximately 2000° C.

The present invention provides a continuous process for producinghydrogen and carbon based on a single-step catalytic decomposition ofhydrocarbons C_(n)H_(m) over in-situ generated catalytically activecarbon aerosol particles (C_(aer)) according to the generic equation asfollows:

C_(n)H_(m)+(C_(aer))→C_(pr)+m/2H₂  (1)

wherein n≧1, and (2n+2)≧m≧n. C_(n)H_(m) is hydrocarbon feedstockincluding, but is not limited to methane, natural gas, propane,liquefied petroleum gas (LPG), naphtha, gasoline, kerosene, jet-fuel anddiesel fuel. C_(pr) is carbon product, which comprises original CAP andcarbon formed during C_(n)H_(m) decomposition and laid down on CAPsurface.

CAP can be produced from a great variety of carbonaceous materials (CM)with the general formula of C_(p)H_(q)X_(r), where X is an elementincluding, but not limited to oxygen, nitrogen, sulfur, phosphorus, andp≧1, q≧0, r≧0.

Non-limiting examples of carbonaceous materials (CM) include all classesof hydrocarbons (saturated, unsaturated, aromatic), and a variety ofoxygen, nitrogen-, sulfur- and phosphorus-containing organic compounds,including, but limited to ethylene, propylene, acetylene, benzene,toluene, acetic acid, propanol, carbon disulfide and mixture thereof,and carbon monoxide (CO).

According to the preferred embodiment of the present invention, CAP canbe formed from CM upon exposure to an energy input, as shown in thefollowing generic equations:

C_(p)H_(q)X_(r)+energy input→C_(aer)+products  (2)

The energy input to the reaction (2) can be provided by non-oxidativeand oxidative means. The non-oxidative means of the energy inputincludes, but is not limited to a high temperature source, such as, ahot filament, a heating element, a catalytic burner, and the like, orplasma (thermal, non-thermal, microwave, a corona discharge, a glowdischarge, a dielectric barrier discharge), or a radiation source(electron beam, gamma, X-ray, UV, and the like).

The oxidative means of the energy input includes, but is not limited to,the use of various oxidizing agents such as oxygen, air, ozone, hydrogenperoxide, NO₂, ClO₂, and the like. In the presence of the oxidants,partial combustion of CM occurs at elevated temperatures, which resultsin decomposition of CM into carbon particles and production ofcombustion products such as water and CO₂ and others according to thefollowing generic equation:

C_(p)H_(q)X_(r)+[O_(x)]→C_(aer)+H₂O+CO₂+other products  (3)

wherein, [O_(x)] is an oxidant.

After the carbonaceous material (CM) is exposed to an energy input fromoxidative or non-oxidative sources in a CAP generator with internaltemperatures in a range of from approximately 100° C. to approximately5000° C., carbon particles are formed that resemble carbon dust whichbecomes airborne and is directed to a catalytic reactor, to catalyze thedissociation of hydrocarbon feedstock into hydrogen gas and elementalcarbon.

A preferred embodiment of the invention is a process for sustainable,continuous production of hydrogen and elemental carbon via catalyticdecomposition of hydrocarbons over in-situ generated carbon aerosolparticles comprising the steps of: generating carbon aerosol particlesfrom carbonaceous materials in response to an energy input in a firstcompartment of a reactor vessel; directing airborne carbon particles toa second compartment of a reactor vessel for catalytic decomposition ofhydrocarbon feedstock over said carbon aerosol particles at elevatedtemperatures in the reactor; recovering a stream of hydrogen-containinggas (HCG); directing said HCG to a gas separation unit where purehydrogen is separated from the stream; recovering carbon product fromthe second compartment of the reactor and collecting it as a finalproduct. An apparatus is also described for carrying out theabove-identified process.

Reference is now made to FIG. 1, which illustrates the general conceptof the present invention. The stream of carbonaceous material 5 entersthe CAP generator 10 where carbon particles or carbon aerosol particlesare produced when carbonaceous material (CM) is exposed to an energyinput 15, which can be provided by non-oxidative, or oxidative means ora combination thereof. A stream of carbon aerosol particles 11 isintroduced into the catalytic reactor 12. The stream of hydrocarbonfeedstock 6 enters the catalytic reactor 12 where its dissociationoccurs during contact with the surface of carbon aerosol particles (CAP)thereby producing hydrogen 16 and carbon 18. Hydrogen gas 16 exits thereactor. Solid carbon particles lay down on the surface of CAP and forma final carbon product 18, which exits the reactor 12.

FIG. 2 illustrates the invention for the first embodiment wherecarbonaceous material (CM) is hydrocarbon, more specifically, ahydrocarbon that is a source of carbon aerosol particles. In thisembodiment of the invention, the hydrocarbon stream 7 is split into twostreams 7A and 7B. Smaller stream 7A enters the CAP generator 10, wherecarbon aerosol particles are produced upon hydrocarbon exposure to anenergy input 15. A stream of carbon aerosol particles 11 is introducedinto the catalytic reactor 12, where dissociation of hydrocarbonfeedstock from stream 7B occurs during contact with the surface ofcarbon aerosol particles (CAP) thereby producing hydrogen 16 and carbon18. Hydrogen gas 16 exits the reactor. Solid carbon particles lay downon the surface of CAP and form a final carbon product 18, which exitsthe reactor 12. It should be apparent to one skilled in the art that theconcept can be applied not only to hydrocarbons, but to any othercarbonaceous material that can produce carbon aerosols upon exposure toan energy input.

The invention is further illustrated by FIG. 3, which provides asimplified schematic diagram of the process for production of hydrogenand carbon from hydrocarbon feedstock. Carbon aerosol particles areproduced in the aerosol production section 21 of the reactor 20. Thestream of carbon aerosols 22 enters the catalytic section 23 of thereactor 20 where carbon-catalyzed decomposition of hydrocarbon feedstockoccurs at 700-1200° C., preferably, 850-1000° C., and pressure 1-50 atm,preferably, 2-25 atm.

The vortex configuration of the reactor 20 allows for an adequate mixingand contact time between the carbon aerosol particles and thehydrocarbon feedstock. The residence time within the reaction zone is0.01-600 seconds (s), preferably, 1-60 s. The concentration of hydrogenin the effluent gas from the reactor 20 depends on the nature ofhydrocarbon feedstock, temperature, residence time and varies in therange of 10-90 volume %, with the balance being mostly methane andhigher hydrocarbons, such as, C₂+, including ethylene and other lightunsaturated hydrocarbons.

The hydrogen-rich gas exits the reactor 20, through a series of cyclones24 and a heat exchanger 25 and is then directed to a gas separation unit(GSU) 26, where a stream of hydrogen with the purity of 99.99 volume %is separated from the gaseous stream. The GSU can include a gasseparation membrane, a pressure swing adsorption (PSA) system, acryogenic adsorption unit, or any other system capable of separatinghydrogen from hydrocarbons.

Non-permeate gas or PSA off-gas is directed to the aerosol productionsection 21 of the catalytic reactor 20 where it is decomposed in thepresence of a non-thermal plasma with the production of hydrogen-richgas and carbon aerosols 22 that enter the reaction zone 23. The recyclegas (or PSA off-gas) consists mainly of unconverted hydrocarbons andpyrolysis products: olefins and aromatics Alternatively, a portion ofhydrocarbon feedstock could be directed to the aerosol-generator 21 toproduce carbon aerosol particles (this option is not shown in FIG. 3).The non-thermal plasma is produced by means of electrodes 28 made ofgraphite or metals and a power source 29.

One of the important findings of this invention is that thedecomposition of olefins and aromatic hydrocarbons generates carbonparticles with particularly high catalytic activity toward hydrocarbondecomposition. In FIG. 3, carbon product 27 is collected in the bottomsection of the vortex reactor 20 in the form of carbon particlesapproximately 100 microns in diameter, and can be continuously withdrawnfrom the reactor and stored in a carbon collector (not shown in the FIG.3). Due to low thermal energy requirements (i.e., endothermicity) of thehydrocarbon decomposition process and elimination of several gasconditioning and catalyst regeneration stages, the overall CO₂ emissionfrom the proposed process would be significantly less than fromconventional processes, such as, steam methane reforming.

FIG. 4 is a perspective view of the reactor of the present inventionshowing the inlet tube 21A connected to the aerosol generating section21 (shown in FIG. 3), the outlet for hydrogen gas 37, the inlet 35 forcarbon particles collected in the cyclone 24 (shown in FIG. 3), inletfor the hydrocarbon feedstock 31, and the carbon product outlet 39.

FIG. 5 depicts the plan view of the reactor 20 for carbonaerosol-catalyzed decomposition of hydrocarbons. FIG. 5 is a view of thetop side showing the inlet for carbon aerosol particles 21A which isconnected to the aerosol generating section 21 (shown in FIG. 3), thehydrogen gas outlet 37, the inlet 35 for carbon particles from thecyclone 24 (shown in FIG. 3), carbon product outlet 39, and thehydrocarbon feedstock inlet 31.

In the second embodiment of the invention an oxidant (e.g., oxygen orair) is introduced to the carbon aerosol particle (CAP) generatingsection 21 of the reactor 20 resulting in the production of a stream ofcarbon aerosols via partial combustion of the hydrocarbon feedstock orthe recycle gas (off-gas). Input of energy in the form of non-thermalplasma or other energy source for the production of CAP in this case isnot necessary. The rest of the procedure is similar to that describedfor the first embodiment. It is apparent to one skilled in the art thatthe invention is capable of other embodiments, for example, anycombination of a non-oxidative and oxidative means of the energy input,such as a combination of non-thermal plasma with oxygen.

Thus, the present invention significantly simplifies the catalytichydrocarbon decomposition process by eliminating the catalystregeneration step, and, thus, improves its efficiency andsustainability. The improvement is achieved by continuous in-situgeneration of catalytically active carbon particles that efficientlydecompose hydrocarbon feedstocks into constituent elements: hydrogen andcarbon. This also allows the elimination or significant reduction inoverall CO₂ emissions from the process.

EXAMPLES

Experiments demonstrated technical feasibility of the present invention.FIG. 6 depicts the schematics of the carbon aerosol generator 21consisting of at least two electrodes 52 placed inside a tubular orother shape vessel 58. Electrodes are made of graphite or a variety ofmetals and/or their alloys, such as iron (Fe), nickel (Ni), copper (Cu),stainless steel, nickel-copper (Ni—Cu) alloy, and the like. A powersource 54 supplies high voltage to the electrodes resulting in thegeneration of non-thermal plasma discharge 50.

Hydrocarbon feed 7 enters the CAP generator 21, and is exposed to thenon-thermal plasma 50 which can create temperatures above 900° C.causing hydrocarbon dissociation and formation of carbon aerosolparticles 56 that become airborne and are carried away by the gaseousstream or drop via gravitational pull into the vortex pyrolysis reactor20.

FIG. 7 is a graph of experimental results of methane decomposition at850° C. using carbon aerosol particles as a catalyst. Carbon aerosolparticles were produced by non-thermal plasma-assisted decomposition ofmethane using graphite and metal (Fe, Ni, stainless steel, Ni—Cu)electrodes. The catalytic activity is expressed as a rate of methanedecomposition per unit of weight of carbon. The carbon aerosols producedwere compared to that of carbon black BP2000, which is astate-of-the-art carbon catalyst exhibiting highest catalytic activitywithin the carbon black family; it has a surface area of 1500 m²/g.

It is evident from kinetic curves presented in FIG. 7 that all samplesof carbon aerosol particles produced demonstrated higher initialcatalytic activity in methane decomposition compared to the baselinecatalysts BP2000. Carbon aerosols produced in the non-thermal plasmadevice with Ni—Cu electrodes showed the highest catalytic activityduring the time interval from approximately 1 minute to approximately 13minutes. The significantly high catalytic activity occurs with no needfor regeneration of the catalyst.

FIG. 8 is a bar graph of the experimental results of methanedecomposition at 850° C. using carbon aerosol particles as a catalyst.In this example, carbon aerosol particles were also produced bynon-thermal plasma-assisted decomposition of methane using graphite andmetal (Fe, Ni, stainless steel, Ni—Cu) electrodes. The catalyticactivity is expressed as a rate of methane decomposition per unit ofsurface area of carbon. The carbon aerosols produced are compared tothat of carbon black BP2000 which is shown on the graph as CB. BP2000 isa state-of-the-art carbon catalyst exhibiting highest catalytic activitywithin the carbon black family; it has surface area of 1500 m²/g.

FIG. 8 shows that carbon aerosols differ in catalytic activity dependingon the material of the electrode used. All samples of carbon aerosolswere catalytically more active than carbon black BP2000 despite the factthat their average surface area of approximately 100 m²/g, was one orderof magnitude less that that of BP2000. Ni—Cu electrodes show a higherlevel of catalytic activity.

FIG. 9 is a scanning electron microscope (SEM) image of carbon particlesproduced from methane exposed to a non-thermal plasma source. The SEMimage shows that carbon particles are in the form of sphericalagglomerates with the particle size dimension of approximately 0.1 μm toapproximately 0.3 μm.

FIG. 10 is a transmission electron microscope (TEM) image of carbonparticles produced from methane exposed to a non-thermal plasma source.The TEM image shows that carbon produced is structurally disordered.

For the first time, a process and apparatus combine the generation ofcarbon aerosol particles that are used as catalysts in a single-step,catalytic reactor where the in-situ dissociation of hydrocarbonfeedstock occurs in the production of hydrogen gas and elemental carbon.The combination of the two processes, namely, the generation of carbonaerosol particles and dissociation of hydrocarbon feedstock, in oneapparatus resulted in a significant improvement in existing processesfor the catalytic dissociation of hydrocarbon into hydrogen gas andcarbon. The need for catalysts regeneration is eliminated, the processis continuous and sustainable and the generation of undesirable carbonoxides by-products is substantially reduced.

While the invention has been described, disclosed, illustrated and shownin various terms of certain embodiments or modifications which it haspresumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

1-16. (canceled)
 17. An apparatus for producing hydrogen and carbon fromhydrocarbon feedstock using a continuous process consisting of: a) areactor vessel having a first reaction compartment for generating carbonparticles connected to a second reaction compartment which is acatalytic reactor for dissociation of hydrocarbon feedstock intohydrogen gas and carbon; b) a means for transporting a carbonaceousmaterial that is converted to carbon particles to the first reactioncompartment where the carbonaceous material is exposed to an energyinput that produces an outgoing stream of carbon particles; c) a meansfor directing the outgoing stream of carbon particles to the secondreaction compartment; d) a means for transporting a stream ofhydrocarbon feedstock to the second reaction compartment wheredissociation of the hydrocarbon feedstock occurs over the surface ofcarbon particles from step d); and e) a means for collecting hydrogengas from a first outlet and carbon product from a second outlet of thesecond reaction compartment.
 18. The apparatus of claim 17, wherein theenergy input of b) in the first reaction compartment achievestemperatures in a range from approximately 100° C. to approximately5000° C. and is provided by at least one of a non-oxidative means, anoxidative means, and a mixture thereof.
 19. The apparatus of claim 18,wherein the non-oxidative means of the energy input is at least one of ahigh temperature source, plasma, and irradiation.
 20. The apparatus ofclaim 18, wherein the oxidative means of the energy input is an oxidantselected from at least one of air, oxygen, ozone and nitrous oxide 21.An apparatus for producing hydrogen and carbon from hydrocarbonfeedstock using a continuous process consisting of: a) a reactor vesselhaving a first reaction compartment for generating carbon particlesconnected to a second reaction compartment that is a catalytic reactorfor dissociation of hydrocarbon feedstock into hydrogen gas and carbon;b) a means for dividing a hydrocarbon feedstock into a first stream thatis converted to carbon particles and a second stream that is dissociatedinto hydrogen gas and elemental carbon; c) a means for transporting thefirst stream of hydrocarbon feedstock of b) to the first reactioncompartment where the hydrocarbon is exposed to an energy input thatproduces an outgoing stream of carbon particles; d) a means fordirecting the outgoing stream of carbon particles to the second reactioncompartment; e) a means for transporting the second stream ofhydrocarbon feedstock of b) to the second reaction compartment wheredissociation of the hydrocarbon feedstock occurs over the surface ofcarbon particles from d); and f) a means for collecting hydrogen gasfrom a first outlet and carbon product from a second outlet of thesecond reaction compartment.
 22. The apparatus of claim 21, wherein theenergy input of c) in the first reaction compartment achievestemperatures in a range from approximately 100° C. to approximately5000° C. and is provided by at least one of a non-oxidative means, anoxidative means, and a mixture thereof.
 23. The apparatus of claim 22,wherein the non-oxidative means of the energy input is at least one of ahigh temperature source, plasma, and irradiation.
 24. The apparatus ofclaim 22, wherein the oxidative means of the energy input is an oxidantselected from at least one of air, oxygen, ozone, and nitrous oxide.